Womb transplants for women 'three years away'

Healthy, fertile mice have been born from mothers with transplanted wombs, Swedish scientists announced on Tuesday. The technique researchers developed to achieve the feat could lead to the first human birth from a transplanted womb within three years, they say.

The team is led by Mats Brännström, at Sahlgrenska Academy at Gothenburg University, and first births of live pups were reported by New Scientist in August 2002. But the latest results show that the offspring are themselves healthy and able to reproduce.

Brännström and colleagues transplanted uteruses into mice alongside their normal uteruses and transferred embryos for implantation two weeks later. The pregnancy rate of 70 per cent was the same in transplanted and normal uteruses, he says.

Womb transplants could help women who are infertile due to uterine problems, offering them an alternative to finding a surrogate mother for their baby. However, as well as the substantial practical difficulties in transplanting a womb, scientists will also need to tackle the problem of immune rejection.

Mothers and sisters

"Potential donors could be the mother or older sister [of the infertile woman] who has had her own babies, or other altruistic donors," says Brännström, who presented the findings at the European Society for Human Reproduction and Embryology (ESHRE) annual meeting in Madrid.

Close relations are more likely to have good immune compatibility, he says. But transplanting a mother's uterus to her daughter would mean the daughter would bear a child in the same uterus in which she herself developed.

Hans Evers, outgoing chairman of ESHRE, said the study "may allow a little hope" for women with uterine infertility problems. But he warns that "the immune system of a mouse is quite different from a human".

Brännström says up to four per cent of infertile women could be helped by womb transplants. These women could be infertile due to congenital uterine problems, such having too small a womb, or may have had a hysterectomy due to illnesses like cervical cancer.

Genetically identical

The Swedish team have taken two years to develop the "extremely complicated" surgery needed to transplant a womb into a mouse. Importantly, says Brännström, the technique tackles the three major problems presented by connecting a new uterus to the body. "There's no nerve supply, or lymphatic drainage, or blood supply," he says.

In the mouse experiments, the researchers avoided the issue of immune rejection by using specially-bred mice that were 99.9 per cent genetically identical.

But Brännström does not envisage major immune rejection problems in humans. "The rejection problem should be fairly simple as it's a fairly simple organ - it's mainly a big muscle tissue with endometrium," he says. "It does not contain large number of lymphocytes like the intestine, which is a problem when transplanting."

Also, many women, such as those with transplanted kidneys, already take immunosuppressant drugs while pregnant and still give birth successfully. The team is conducting studies in pigs to look specifically at immune rejection and in human uterine tissue to examine its resilience to cold preservation.

This is of particular importance, says Lynn Fraser, chair of ESHRE's international scientific committee. "In real life we would take a donor uterus out and there would be some sort of lag before it was put in the recipient." But she adds: "The hardest part may be to find the donor organs."

The first human womb transplant was performed in Saudi Arabia in 2000. However, doctors had to remove the womb after 99 days because the blood supply had failed. This was a "disaster", says Evers.

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